1. Field of the Invention
A gearless locking differential includes clutch members having V-shaped slots that cooperate with a cross pin to disconnect from the differential drive shaft an overrunning driven shaft, characterized in that the wall surfaces that define the V-slots extend parallel with the axis of rotation of the differential housing, and the cross pin has tapered convergent end portions. The frictions packs that releasably connect the side gears to the clutch housings include annular friction plates that are arranged between pairs of reaction plates and include polygonal internal circumferential surfaces that slidably and non-rotatably engage a corresponding polygonal circumferential surface on the associated side gear. The locking lug and the locking slot which cooperate to provided limited angular relative displacement between the clutch housings each have parallel side walls. As a consequence of the invention, the machining and finishing of the differential components is achieved in a simplified cost-effective manner.
2. Description of the Related Art
Locking differentials for automotive vehicles are well known in the patented prior art, as evidenced by the patents to Lewis U.S. Pat. No. 2,555,044, Zentmyer U.S. Pat. No. 5,413,015, and Valente U.S. Pat. Nos. 5,590,572 and 5,727,430, and Dissett U.S. Pat. No. 5,715,733, and Dissett et al U.S. Pat. No. 6,6988,194.
In these known differentials, it is common to utilize a pair of annular coaxially-arranged axially-spaced clutch members arranged on opposite sides of a diametrically extending driving cross pin that extends within mating cam grooves contained in the adjacent faces of the clutch members. Spring means normally bias the clutch members apart, and a locking pin extends axially from one face into a recess contained in the adjacent face of the other clutch member, thereby to prevent relative rotational movement between the clutch members. The locking pins are generally separate components, used in connection with a plurality of biasing springs and spacer disks or plugs, thereby causing assembly of the differential to be relatively labor intensive and manually difficult.
In the original design shown in the Dissett et al U.S. Pat. No. 6,688,194, it was necessary o manufacture the “V” ramps on the clutch housing in a skewed manner in a very complicated three dimensional plane. This was required for the cylindrical shaped cross pin to make a full line contact on the “V” ramps of the clutch housing, at the point where all of the end-play from the clutch housing to the differential case was taken up, allowing a good distribution of the loading and full clutch pack lock-up. As the cross pin rotates relative to the clutch housing, it runs up the ramp on the clutch housing and moves the housing in an outward direction locking up the clutch pack. This movement allows the torque to be transferred from the clutch housing to the side gear and then to the axle shaft.
The present invention was developed to provide an improved locking differential that is less expensive and easier to produce and inspect, and which affords improved relative sliding movement between the components of the friction packs, whereby the possibility of binding of the components is greatly reduced. According to the present invention, the clutch housing and the side gears can be completely manufactured from powdered metal with no secondary machining required. These two major components can also be cold or warm forged for higher load applications with much less secondary machining that the prior art production design. The improved design of the friction and reaction plates as well as the inner spacer have been designed to simplify the manufacture thereof and to improve the smoothness of the energizing and de-energizing of the friction reaction plates by allowing them to slide easier on the side gear and in the clutch housing, respectively. For lower volume manufacturing needs, all the slots, keyways and keys have been designed with straight and parallel sides, thereby to allow for simple milling operations. It will also be easier to inspect these components.